This invention relates to fluid power operated devices and more particularly to automatic hydraulic cylinder control by directional control valves.
In many applications it is desirable to manually start a hydraulic cylinder cycle and have the system complete the cycle without further attention by the operator. An example is that of a refuse pick-up truck in which refuse is dumped into a hopper and the system activated to compact this material. It is desirable to have the cylinder complete its compacting stroke, return the gate to its retracted position and then return the directional control valve to its neutral position deactivating the hydraulic system.
The Tennis U.S. Pat. No. 2,848,014 discloses a semi-automatic directional control valve in which the valve will move automatically from an active to the neutral position in response to build up in pressure at the hydraulic cylinder. However, use of such a valve on an application as described required two manual operations, one to compact the material and the other to return the gate to open position.